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Author Topic: led laser tail light  (Read 3211 times)

Offline zhephyr

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led laser tail light
« on: 10/07/2013 08:44:52 »
new laser tail light

Very few people know that traffic law indicates that bicycles must maintain at least 1.5m lateral distance when overtaking bicycles.
This light should help (at least overnight) people to visualize it.

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Offline RD

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Re: led laser tail light
« Reply #1 on: 10/07/2013 09:19:27 »
Does it remove car door mirrors light-sabre style ? :)

But on a serious note ... what if the laser is reflected upwards by some chrome, like the wheel rim of another bicycle, or a chrome bumper, would it then be possible for the laser beam to dazzle/blind another road user ?
« Last Edit: 10/07/2013 09:46:31 by RD »
 

Offline CliffordK

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Re: led laser tail light
« Reply #2 on: 11/07/2013 00:37:41 »
A person likely wouldn't stay in the "spot" of the taillight for long, but I certainly wouldn't want to see lasers being used a lot in auto taillights.  I'm doubting that a driver would pay much attention to the bicycle lights for clearance.  I usually give the bicycles as much room as it is safe to do so.

When I was pulling a baler (obnoxiously wide) at night, I did add some low pointing fog lights near the wheels to help me see where the baler was on the road.

On another trailer, I replaced the fender lights with LEDs.  The yellow forward facing ones were so obnoxiously bright in my mirrors that I am now removing them.
 

Offline Don_1

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Re: led laser tail light
« Reply #3 on: 30/07/2013 16:25:14 »
The advantage of an incandescent lamp is that it can be seen from all angles. Spotting a laser, unless it is directly ahead of you and pointing in your general direction, may not be so easy, especially on clear nights.

I think this a bad idea. It would be far better to educate cyclists to use lights at night and cycle with due care. If I had a pound for every cyclist I have seen at night with no lights whatsoever, ignoring traffic signals, going the wrong way on a one way street, ignoring pedestrian crossings, going like a bat out of hell down steep hills etc etc etc I would be a rich man.
 

Offline CliffordK

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Re: led laser tail light
« Reply #4 on: 30/07/2013 20:59:42 »
The lasers, of course, are making a mark on the pavement which is visible at many angles.  But, it is a good point that I'd much rather have myself and my bicycle visible rather than a spot on the pavement behind me being visible.

Flashing lights are good at attracting attention, as well as lights on pedals and legs that impart movement.

Another interesting newer invention are the induction bicycle lights that have a non-contact generator using very little power, no batteries (although perhaps a short-term capacitor), and blinks when one rides.  Also see Magnic light that works without an added magnet.
« Last Edit: 30/07/2013 21:33:37 by CliffordK »
 

Offline CliffordK

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Re: led laser tail light
« Reply #5 on: 30/07/2013 21:27:08 »
Apparently in the UK, there is also a DIY Induction magnetic bicycle light kit.  If you don't mind a little electrical tape on your bicycle, it looks like a great kit.
 

Offline RD

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Re: led laser tail light
« Reply #6 on: 31/07/2013 20:31:11 »
Apparently in the UK, there is also a DIY Induction magnetic bicycle light kit.

Quote from: freelights.co.uk
No Batteries - Ever! No Friction! No Batteries - Ever! No Friction! No Resistance!!

Even if there really was "No Friction!", (which isn't true) , there would still be resistance to motion, (an electromagnetic braking action), when a magnet passes close to metal, e.g. ... https://en.wikipedia.org/wiki/Lenz_law#Example

see ...
[:0]
« Last Edit: 31/07/2013 20:52:04 by RD »
 

Offline CliffordK

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Re: led laser tail light
« Reply #7 on: 02/08/2013 03:34:09 »
Apparently in the UK, there is also a DIY Induction magnetic bicycle light kit.

No Batteries - Ever! No Friction! No Batteries - Ever! No Friction! No Resistance!!

Even if there really was "No Friction!", (which isn't true) , there would still be resistance to motion,

A educational kit for investigating electrical generator in schools and colleges.

Uhhh...
And they are wanting (UK) schools to teach that powering the lights requires no resistance???  RD, perhaps you should write a letter to them and set them straight.

Friction, however, is considered a "contact force".  So, other than some wind resistance components, the induction magnets would be non-contact, and thus no friction.

I have, however, used the old tire generators, about 6 watts, what a pain to pedal. 
The LEDs, of course, use minimal power, especially if only on for a fraction of the time.  I have tried the Reelights, and the resistance is hardly noticeable.  A (relatively) heavy tire with good bearings can spin quite a while wile generating sufficient power to make the lights blink. 

One of the Reelights does use a capacitor (I think) to allow the lights to continue flashing while a person is stopped briefly.
 

Offline RD

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Re: led laser tail light
« Reply #8 on: 02/08/2013 10:52:58 »
... RD, perhaps you should write a letter to them and set them straight.

Looks like someone has already done that …

Quote from: freelights.co.uk
Note: Some people wrote to us, saying they do not believe there is no drag in this dynamo. Technically, there is a drag force but only between the two magnets. Unlike typical dynamos there is no scraping against the tire to slow down the bike itself. On a real bicycle, even the drag force between the two magnets is too small to be detected
http://www.freelights.co.uk/how.html

the electromagnetic drag would also occur when the magnet on the spokes passed the metal frame of the bike (even if he bike frame was aluminium like the aluminium tube).

The electromagnetic drag could be “detected” by turning the bike upside down, allowing the front wheel to come to  rest , rotating it 180 degrees, letting it go and timing how long the oscillations took to die away , with and without a magnet attached, [ should replace the magnet with  a non-magnetized bit of metal of the same size and weight for a fair comparison ]. 
« Last Edit: 02/08/2013 11:06:37 by RD »
 

Offline CliffordK

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Re: led laser tail light
« Reply #9 on: 02/08/2013 19:09:44 »
The electromagnetic drag could be “detected” by turning the bike upside down, allowing the front wheel to come to  rest , rotating it 180 degrees, letting it go and timing how long the oscillations took to die away , with and without a magnet attached, [ should replace the magnet with  a non-magnetized bit of metal of the same size and weight for a fair comparison ]. 
Perhaps I'll have to dig out the light kit I have and give it a whirl.

One could leave the magnet attached to the spokes and just add or remove the pickup coils.  the magnet could still interact with the forks or other components (unless you chose to remove that factor too).

If the drag is low, then one would have to have an ability to set a constant start speed.  Just spinning the tire wouldn't be enough, especially if it is not a blinded trial.  Perhaps using an electric motor rubbing on the tire to spin up the wheel.
 

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Re: led laser tail light
« Reply #9 on: 02/08/2013 19:09:44 »

 

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